1. Field of the Invention
The present invention relates to an imaging lens and an imaging apparatus, and more particularly, to an imaging lens suitable for, for example, an in-vehicle camera, a camera for a portable terminal, and a monitoring camera using an imaging device, such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), and an imaging apparatus including the imaging lens.
2. Description of the Related Art
In recent years, the size of an imaging device, such as a CCD or a CMOS has been significantly reduced and the number of pixels thereof has significantly increased. In addition, the size of an imaging apparatus body including the imaging device has been reduced, and there is an increasing demand for an imaging lens with a good optical performance and a small size. For example, there is a demand for a lens that is provided in, for example, the in-vehicle camera or the monitoring camera and has a small size, high weather resistance, a light weight, and a low manufacturing cost.
For example, JP-A-2002-244031, JP-A-2005-227426, JP-A-2006-259704, and JP-A-2007-206516 disclose an imaging lens including a relatively small number of lenses, which has been known in this field. JP-A-2002-244031, JP-A-2005-227426, JP-A-2006-259704, and JP-A-2007-206516 disclose an imaging lens having four lenses including an aspheric lens.
However, in recent years, there is an increasing demand for a wide-angle lens provided in, for example, the in-vehicle camera or the monitoring camera, in addition to the above-mentioned structure demands. However, as in the related art, when only the angle of view of the lens is increased, the effective diameter of a lens that is arranged closest to the object side increases with the increase in the angle of view and the diameter of the lens increases, which makes it difficult to reduce the size of the lens. In particular, in the in-vehicle camera or the camera for a portable terminal, there is a demand for a lens in which a small portion is exposed to the outside such that the outward appearance does not deteriorate. Therefore, there is a strong desire to reduce the size of the lens system in the diametric direction. For example, in the monitoring camera, it is necessary to reduce the size of the lens system in the diametric direction in order to make the camera as invisible as possible. That is, there is a demand for a lens system capable of meeting two opposite requirements, that is, an increase in the angle of view and a reduction in the size of the lens system in the diametric direction.